Apparatus for the projection of light



Oct. 7, 1930. L. R. MORSHEAD APPARATUS FQR "mm PROJECTION OF LIGHT Filed Jan. 3, 1930 4 Sheets-Sheet l w M m I Oct. 7, 1930.

L. R. MQRSHEAD APPABATUS FOR THE} PROJECTION OFLIGHT Fi e fl- 1950 4 Sheets-Sheet. 2

lllllllul.

'llll Inventor L. R Mora/wad y A). 5- W Aftoruey.

Oct. 7, 1930. L. R. MORSHEAD 1,777,805

APPARATUS FOR THE PROJECTION OF LIGHT Filed n- 5, 1950 4 SheetsSheet s I Inventor L.R.Mors/zead y 4 2 29....

Attorney- APPARATUS FOR THE PROJECTION OF LIGHT Filed Jan. 3, 1950 4 Sheets-Sheet 4 Fig.4.

inventor L.R.N0r.s/7ead= by i a. s W1 I "Attorney.

Patented Oct. 7, 1930 rinsrmnonnnr MonsHnAn, or LoNnoiv, memes APrAnATus non Tl- LE geants mm j Application med January 3, 1930," Serial no. 418,375, and a Great Britain December 29, 1928.

This invention relates to apparatus for,

the projection of light in which converging crossing beams are produced such as are ob tained by projector-apparatus comprising a 5 plurality'of concentrically disposed truncated ellipsoidal reflectors having their foci co1ncident, which may be 'used in conjunc tion with a retracting system adapted tore tract the cone otrays which do not fall upon i0 thereflector system,and with a hemispherical reflector disposed to the rear of the saidrefiectorsystem with its centre of curvature-at the said coincident foci, a source of light being disposed atthe said coincident foci.

15 Such a projector system is described in the x2e; utilize with full advantage thewhole of the light obtained from a source of light suchas an electric incandescent lamp when operatingin conjunction with a rearhemispherical Except when employedfor open" m flooding purposes, other known types of apreflector.

, paratus for spot or'flood lighting which, as is normally required, project a full beam without a central dark zone, necessarily op erate at a considerable] disadvantage in loss as ofintensityin the projectedbeam, which'disadvantage increasesas thebeam angle is reduced. p j The apparat-s usually employed for spot 1 or flood lighting, more particularly forproac, jecting. beams of angles varying from, say, 90 tolzero orparallel, is of a simple type consisting of asource of hght, such as an are or incandescent lamp, adj'usta'bly mounted behind a focussing system, comprising a as simple or compound lens arrangement, the:

sourcetof light in \the case, of incandescent lamp projection being provided with t a rear hemispherical reflector, which isofcoursel not required or utilized in 'the'case of elec so tric arc'projection-L W th such spot or flood lighting, if a relatively wide angle projected beam be required it is "obtained by moving the source of light'close up to the frontal lens, or focussing system, with the consequence that very heavy losses intransmitted light' ntenslty resulty nasmuch as under no conditions can the Whole zone of light emitted from the 'source'be utilized byany available type of projecting lens. l/Vhen, however, an extremely narrow beam approachingto parallel is required, a relatively much greater loss oflight results owing to thefactthat'the sou rceof light must be removed a consider able distance away from the projectingl ens, which therefore utilizes a-much smaller proportion of the whole zoneot emitted light;

According to the present invention converging crossing beams are utilized, for which purpose the optical projection system is so provided inrelation to the source of light that a large proportion of the? total light emitted by the source of light employed is projected in a highly intense beam ofrela tively narrow angle.

-According to the invention a lens is ad+ justably mounted in relation to and -in front of the optical projection system in a position forward of the crossing point of-theconverga ing beam {derived from the projection system, It may, however, be so, provided as to be adapted to move also *to the rear otftheflsaidf crossing point,

A cording to the inventiommoreover, the

projector is provided with an aperture which maybe adjustable and which servesto focus or control the converging beam, the said aperture being adapted to be positioned at the point o fcrossin'g of the beam, or a position adjacent thereto. 1 Thus, when. the

aperture is positioned atthe point of cr'oss- P in-g Wherethe beam has a core or inner portion of high intensity, the aperturecrrray be adjusted to permit of the focussing of lthe beam to a sjfiot light of unusually narrow a angleof highfintensity, while it the aperture be movedrearwardly of the point of crossmg, it be usedto control the ata point at whichit. is of a more uniform, if, less intense, character, so tlrata. focussed spot light of wider angle, but of less intensity, may be obtained.

The invention is especially applicable to an equivalent spherical light source, such as an electric incandescent lamp which may thereby be substituted for the electric are now still largely employed for theatre, studlo, and other types of spot and flood lighting Where high intensities of illumination are required with long throws and with large areas.

The invention is, however, applicable to are projection with respect to which the invention has among its objects to obtain efliciency in the use of existing types of light projection apparatus.

The invention comprises thefeatures of method and apparatus hereinafter described.

The accompanying diagrammatic drawings illustrate a projector provided in accordance with the invention, by way of exam le.

igure 1 is a sectional side elevation of the projector.

Figure 2 is an end View corresponding to Figure 1. V

Figure 3 is a diagrammatic sectional elevation of a construction of motor head lamp according to the invention.

. Figure 4 is a corresponding crosssectional elevation taken on the line l4: ofFigure 8.

In carrying the invention into effect arelatively small diameter lens a of suitable refracting power is selected and is adjustably mounted in relation to and in front of the optical projection apparatus 1) from which the crossing beam is derived, including the source of light 0. Assuming that the lens a is a positive lens of a simple type such as Plano-convex, or bi-convex, and is located concentric with and at the crossing point of the projected beam, it will have a negligible refracting effect, and therefore will not change the beam angle. If, however, the

lens is' advanced beyond the crossing point away from the source of light it will refract the beam to an increasing extent in proportion to its advancement. until it reaches a limit in accordance with its refracting power and focal length. Under these conditions, if the angle of the crossing beam is suitably related to the refracting power of the objective lens a substantially parallel beam is projected suitable for spot lighting, in which thefull power and intensity of the projected beam is efficiently employed.

If the lens is now brought back towards the crossing point, the emerging beam opens out to an angle which may be suitable for enlarged spot or flood lighting. When the crossing point is again reached, the beam will be projected at full angleas derived from.

its projection apparatus which, in many cases, will be sufliciently wide to meet the maxlmum requirements of flood lighting.

If, however, it be desired to open out the emerging beam angle still further for wide angle flooding, the lens may be moved behind the crossing point towards the source of light, with the result that the emerging beam angle will gradually be increased beyond the normal angle of projection.

It will be understood that the lens or focussing system may be either adjustably mounted in relation to the source of light and its accessory optical system or that, alternatively, the latter system may be moved in relation to the frontal lens, or focussing system, so as to produce any desired variations in beam angle within the limits of the combined apparatus.

In the projector illustrated the lens a is suitably supported so as to be adjustable relatively to the casing of the projector system b which may be of the kind hereinbefore described adaptcd to give a highly intense converging and crossing beam of light as indicated in dot and dash lines in Figure 1. For this purpose the base plate 6 of the easing is extended forwardly but of reduced cross-section and provided at the extremity with laterally disposed bearings for two parallel rods a which are suitably connected at intervals by transverse tie members to form a substantially rectangular frame that is longitudinally slidable in the base plate I). At the forward end the rods a are connected by a transverse upstanding fitting a" which may be in the form of a cast bracket serving to support the lens carrier a conveniently in the form of a front cylindrical or conical casing member, having the lens mounted at the forward end. The carrier a is advantageously removable from the fitting a to permit other carriers with lenses of differing focal lengths to be used.

To permit the lens carrier a to be adjusted in position relatively to the projector Z), the rods a are adapted to be moved longitudinally in the base plate 6 by means of a bell crank lever a pivoted to the base plate 6 upon a pivot pin 6 and linked by means of a link a to a pin a mounted upon one of the transverse members connecting the rods a The lever is providedwith an operating handle a whereby the lever a and link a may be moved for the adjustment of the position of the rods a A locking nut with handle b is mounted upon the pin 6 According to the invention, also, a diaphragm (Z, for example, of the iris type, is adj ustably positioned between the lens a and the front plate 6 of the casing 6 in which is formed the beam aperture. As is illustrated in Figure 1, a plate'@ is mounted upon the plate 6 in a position parallel thereto, by means of bolts 6 and distance pieces 6 the plate '0 being formed with an aperture for the passage of'the beam of light. At the top the plate 6 supports a rod d upon which is slidably suspended' a barrier for the dia-.

phragm (Z,"the said carrier comprising two plates 6?, Z disposed parallel, to one 'of which, (i the'diaphragm casing is secured, while the other, (Z is positioned in spaced-1e lationthereto by suitable retaining bolts 'd and distance pieces d At the lower end the plate d is secured to a bracket member d in which is slidably and rotatably mounted,

by means of a rotatable bush, a squared spindle fclythe rear part of which is rotatably mounted in the base plate 6 and is provided at the rear end with anoperating handle (i The'g lower part of thefitting a is recessed or cut awayto admit the bracket member d".

The 'sizeo't aperture of the diaphragm (Z is controlled by means ofa link (Z 01 curved shape wliiclris-connected to a curved and bent arm or lever d secured to and adapted torotate with the bush beforereferred to upon rotationflof the rod d Thus, by movement oi the handle (Z the diaphragm may beadjusted within the trontlens carrier, casing member maybe used for cutting out or :torthe pro.

or section a andwthe plate a, a cylindrical screen (Z carried by the plane 6 telescoping with a corresponding screen or rear casing member or section 6 carried by the plate (P. The casing members or sections a and e? form a sectional light tube carrying the refracti'ng lensand between which the diaphragm is disposed, as shown, and the part c of the lens carrier and the'part'dl form at'elescopic light tube allowing ad ustment of the lens a with relation to the light sourcewithout loss or light,

Thedistance pieces serve toposition be tween the plates?) and c a slidewayho'lder or carriere for an obturator discor plate which tection of the diaphragm (Z against undue heating when the beam isnot actually being.

projected. The spaces represented? by the distance pieces 6 may serve for the reception of colour slides, filters or the like. A- reflector f, shaped as. a'sector of a sphere, having-its centre. of curvature at the said focus is carried to the rear of-the sourceof light c. For

this purpose it'is advantageously provided to be removably supported upon a pedestal in such. manner that it may be mechanically registered in the correct position, a locklng pin 7, for example, serving to determine this position. The pedestal f may also serve to carry an adjustable support for the light source, comprising "a clamp or like device 0 adjustable on the pedestal f andclamping arms a? which arelaterally adjustable and which engage the socket for the lamp, the vertical position ofwhichisdetermined by an adjustable supporting. screw 0 The pedestal f and the screw 0 are conveniently mount-' ed upon a removable platform I)" V provided upon" the base plate I)? and secured in position by bolts Z), the position of the platform being also determined by suitable means such.

as aregistering pin.

By means of the diaphragm d, a sharply focussed spot of light may be obtained of any desired size less than thatsecured'with the emerging tocussedbeam approximately par allel and the ad ustable aperture wide open.

It is advantageous to mount the colour slides or filters at the position determined by the slideway 6, since the converging beam is of large area and therefore gives a minimum concentration of heat. Provision may be made, however, "for the mounting of rotating coloured discs in position adjacent the lensa.

For this purpose the fitting a may serve also to carry the said discs or their mounting; In the position that is indicated in Figure l, the apparatus is adjusted for transportandr also in the position in which it may be used for flood lighting, the aperture'lofthe diaphragm d being fully opened, Theadjusted positions of the diaphragm may be deter mined bymeans of recesses or cutsformed in the rod d withwhich may-engagea locking pin or catch mounted upon the-plate (Fe The invention is applicable to motor head lamps'and for this purpose maybe carried out in the: manner that is indicated inFig ures 8 and dot the accompanying drawings. 1

In this construction, in order to ensure the ad ustment of the emergingbeam angle be tween wide limits, varying from an approximately parallel. uniformlyilluminated and sharply tocussed beam with proportionately high intensity of illumination to a wide 'an-' gleflooding beam witha relativelylow intensity of illumination and consequent, reduction 111 glare, a greatrange of relative adjustment may. be provided between the frontal lens and the projector system, so that the crossing point of the beam may be located on either side oftheirontal lens. The opticalpro ector system,.includ1ng the source of;

light producing the a converging beam, is ad vantageously completely encased by a (casing g, andthediaphragm or aperture 72, iscarried in a fixed position to the rearof the crossing point by means of I a spider-like fitting for alflllsjt and the lens a 1sca rr1ed1'n;acylindria cal carrier/5 sli'dably mounted in the casing 19 I and secured to an annularisupporting ring 2' slidably positioned upon three rods 9 dis; posed parallel with the axis of the system and maintained in the innermost position by means of helical tensionspringsg disposed upon the said 'rjods. The adjustment of positionwof the lens carrier is effected by means of two levers 7' having a transverse pivotal axis in the upper art of'the casing g and adapted to be operated by such means as a Bowden wire connection to draw the lens vcarrier backward against the resistance of I the springs g from the control point. The

lens a is maintained of relatively small diameter in order to avoid the use of a lens of considerable thickness. The source of light is conveniently mounted in the rear portion of the casin in such manner as to be vertically adjustable. By such constructions as indicated, the frontal lens may be adjustably mounted in line with the projected converging crossing beam so that its position may be readily changed to alter the beam angle by means of the operating device controlled from the dash board. Vi ith such a motor head lamp, the full illumination could be utilized under all conditions with considerable possible economies in the size and capacity of the lamps employed, and in such manner that varying beam angle and intensity, with corresponding effects upon glare, would at all times be under the ready and instantaneous control of the driver.

The utility of the invention is not confined to the use of a positive lens of a simple type having the effects hereinbefore described. Thus, if a lens or lens combination of a negaive type were employed, such as a plane-concave or double concave lens, inverse effects may be obtained on account of movement in relation to the crossing point of the beam. Such a negative lens interposed between the optical projection apparatus and the crossing point of the beam would tend to open out the converging beam towards the parallel, whereas, when located in front of the crossing point away from the source of light, it would open out the diverging beam tending to make it cover a wide flooding angle. One possible advantage of the use of this type of lens would be to shorten the overall length of the apparatus employed, when used for certain forms of spot or fiood lighting, and the like. Another important advantage of the use of a negative lens is the fact that there is no projection of an image of the source of light or the projector system under any conditions of use. It will be observed that in the structure shown in Fig. 1 the diaphragm (Z has its aperture within the light tube, and that in the structure shown in Fig 3 the diaphragm ]L is located within the light tube, thereby preventing light losses around the diaphragm and ensuring the passage of all light entering the light tube through the diaphragm aperture.

It will be understood that the constructions of apparatus hereinbefore described may be modified without departing from the invention. Thus, the adjustment of position of the diaphragm (5 may be effected mechanically by means such as the lever and link motion provided for the adjustment of the lens a.

Alternatively, the adjustment of the lens a may be effected by hand without the use of a link and lever motion.

I claim:

1. An apparatus for the projection of light, more particularly for spot and flood lighting and like purposes, comprising a casing having a light projecting aperture in its front wall, an optical projector carried by the casing for producing a converging beam of high intensity having a crossing point, an apertured plate fixed to the front wall of the casing, guides carried by the casing and said apertured plate, a lens carrier frame adjustable on said guides toward and from the optical proj ector, a light tube comprising telescopic sections respectively carried by the apertured plate and lens carrier, a refracting lens carried by the latter-named light tube section, and a diaphragm with aperture of adjustable diameter within the light tube and adjustable with the lens carrier so as to bedisposed at the crossing point of the beam to determine the projection of a beam of high intensity of narrow angle or to be disposed at a position to tne rear of the crossing point of the beam to determine a beam of wider angle and less intensity.

2. A light projecting apparatus of the character set forth in claim 1 wherein tubular light screens are arranged on opposite sides of the diaphragm and telescope the respective sections of the telescopic light tube.

3. A light projecting apparatus of the char acter set forth in claim 1 wherein a holder for interchangeable obturator disks is mounted between the front wall of the casing and the apertured plate.

4. An apparatus for the projection of light, more particularly for spot and flood lighting and like purposes, comprising a casing, an optical projection system carried thereby for projecting a converging beam of high intensity having a crossing point, a light tube receiving said beam and embodying telescopic sections, one adjustable toward and from said optical projection system, a diaphragm having an aperture, said aperture being within said light tube, thereby preventing light losses around the diaphragm, and a retracting lens carried by the adjustable section of the light tube whereby the lens is adjustable with relation to the optical projection system and whereby the diaphragm is rendered variable as to position between the optical projection system and lens.

LESLIE ROBERT MORSHEAD. 

